钙钛矿型LaxSr1－xNi1－yCoyO3光电催化活性研究

用甘氨酸-硝酸盐燃烧合成法, 制备La_xSr_1－xNi_1－yCo_yO₃复合氧化物的陶瓷粉末, 对钙钛矿氧化物进行了XRD结构分析. 在通氧或不通氧下测试氧还原和氧析出的循环伏安曲线. 结果表明: 该氧电极具有双功能催化特性, 但不完全可逆. 利用汞灯作为激发光源, 进行几种水溶性染料和五种混合染料光解实验, 利用紫外-可见、红外以及人工神经网络光度法研究La_xSr_1－xNi_1－yCo_yO₃的催化性能. 结果表明: La_xSr_1－xNi_1－yCo_yO₃ (x＝0.7, 0.9, 1; y＝0.3, 0.75)复合氧化物都具有较强光催化特性; La_xSr_1－xNi_1－yCo_yO₃的光催化活性高于La_xSr_1－xNiO₃, 这与B位离子(Ni^2—, Co^2－)的电子构型有关; Co^2＋的加入可使La_xSr_1－xNiO₃的光催化活性有所提高.     

空气中合成固溶体荧光粉Ba2(Zn, Mg)Si2O7:Ce3+,Eu2+,Eu3+及其发光特性

采用高温固相法在空气中合成了Ba_1.97-yZn_1-xMg_xSi₂O₇:0.03Eu,yCe³⁺系列荧光粉。分别采用X-射线衍射和荧光光谱对所合成荧光粉的物相和发光性质进行了表征。在紫外光330~360 nm激发下,固溶体荧光粉Ba_1.97-yZn_1-xMg_xSi₂O₇:0.03Eu的发射光谱在350~725 nm范围内呈现多谱峰发射,360和500 nm处有强的宽带发射属于Eu²⁺离子的4f⁶5d¹-4f⁷跃迁,590~725 nm红光区窄带谱源于Eu³⁺的⁵D₀-⁷F_J (J=1,2,3,4)跃迁,这表明,在空气气氛中,部分Eu³⁺在Ba_1.97-yZn_1-xMg_xSi₂O₇基质中被还原成了Eu²⁺;当x=0.1时,荧光粉Ba_1.97Zn_0.9Mg_0.1Si₂O₇:0.03Eu的绿色发光最强,表明Eu³⁺被还原成Eu²⁺离子的程度最大。当共掺入Ce³⁺离子后,形成Ba_1.97-yZn_0.9Mg_0.1Si₂O₇:0.03Eu,yCe³⁺荧光粉体系,其发光随着Ce³⁺离子浓度的增大由蓝绿区经白光区到达橙红区;发现名义组成为Ba_1.96Zn_0.9Mg_0.1Si₂O₇:0.01Ce³⁺,0.03Eu的荧光粉的色坐标为(0.323,0.311),接近理想白光,是一种有潜在应用价值的白光荧光粉。讨论了稀土离子在Ba₂Zn_0.9Mg_0.1Si₂O₇基质中的能量传递与发光机理。     

CeCl3-CdCl2-H2O和CeCl3-CdCl2-HCl-H2O的相平衡

测定了三元系CeCl₃-CdCl₂-H₂O (25 ℃)和四元系CeCl₃-CdCl₂-HCl(～8.4％)-H₂O(25 ℃) 的相平衡溶度数据,绘制了相应的溶度图.该三元系是由5个固相区CdCl₂&;#8226;2.5H₂O(原始盐)、CdCl₂&;#8226;H₂O(原始盐)、6CdCl₂&;#8226;CeCl₃&;#8226;14H₂O、4CdCl₂&;#8226;CeCl₃&;#8226;12H₂O、CeCl₃&;#8226;7H₂O(原始盐)组成的复杂体系.该四元系是由5个固相区CdCl₂&;#8226;H₂O(原始盐)、9CdCl₂&;#8226;CeCl₃&;#8226;19H₂O、6CdCl₂&;#8226;CeCl₃&;#8226;14H₂O、4CdCl₂&;#8226;CeCl₃&;#8226;12H₂O、CeCl₃&;#8226;7H₂O(原始盐)组成的复杂体系.其中6CdCl₂&;#8226;CeCl₃&;#8226;14H₂O在该三元系是介稳化合物.9CdCl₂&;#8226;CeCl₃&;#8226;19H₂O 、6CdCl₂&;#8226;CeCl₃&;#8226;14H₂O和4CdCl₂&;#8226;CeCl₃&;#8226;12H₂O用X射线粉末衍射及TG-DTG和DSC等方法进行了研究,并对X射线粉末衍射进行了指标化.     

纳米钙钛矿LaxSr1-xFe1-yCoyO3复合氧化物的制备和表征

用甘氨酸-硝酸盐燃烧合成法，制备La_xSr_1-xFe_1-yCo_yO₃复合氧化物的陶瓷粉末，对该钙钛矿型氧化物进行了XRD、IR、紫外漫反射光谱及循环伏安曲线分析。结果表明：该复合氧化物粉体平均晶粒为15.3～29.8 nm,为立方和正交晶系。该氧电极具有双功能催化特性，但不完全可逆。对水溶液染料进行光解实验，利用紫外-可见、人工神经网络光度法研究La_xSr_1-xFe_1-yCo_yO₃的催化性能。结果表明：CO²⁺的加入可使La_xSr_1-xFeO₃的光催化活性有所提高，B位离子(Fe³⁺，CO²⁺)改变与加入，使La_xSr_1-xFe_1-yCo_yO₃(x=0.7，0.3；y=0.3，0.9，1)光催化活性高于La_xSr_1-xFeO₃。同时，对5种染料进行紫外光解，在0.75 h，脱色率大于91%，并为动力学一级反应。     

层状O2结构锂锰氧化物Li0.60[MgxCoyMn1-x-y]O2的制备及结构表征

本文采用离子交换法分别制备了双复合锂锰氧化物Li_0.60[Mg_xMn_1-x]O₂(0.05 ≤ x ≤ 0.15)和三复合锂锰氧化物Li_0.60[Mg_xCo_yMn_1-x-y]O₂(x=0.05，0.05 ≤      

La-Ce对PbTiO3陶瓷气相扩渗生成La2Ti6O15CeTi21O38的陶瓷材料及其电性能

报道了采用气相法对PbTiO₃陶瓷扩渗La-Ce混合稀土元素的研究. 在气相扩渗过程中, La, Ce与PbTiO₃陶瓷组元发生了复杂反应,生成了稀土化合物La₂Ti₆O₁₅和CeTi₂₁O₃₈, 制备出未见报道的La₂Ti₆O₁₅-CeTi₂₁O₃₈-PbTiO₃陶瓷材料, 经测试其导电性能发生了十分显著的变化. La₂Ti₆O₁₅-CeTi₂₁O₃₈-PbTiO₃陶瓷材料的室温电阻率从2.0 ×10¹⁰ W·m下降为0.248 W·m,而且随着温度的变化, 晶粒电阻呈现明显的PTCR效应,而晶界电阻随着温度的升高,呈急剧连续降低状态,总电阻的变化规律与晶界电阻的变化相一致, 试样总电阻的PTCR效应已不存在, 近趋导体. 经XPS测试分析, 进一步证实了La₂Ti₆O₁₅-CeTi₂₁O₃₈-PbTiO₃陶瓷材料中铅、钛等元素均有变价, 因而导致了La₂Ti₆O₁₅-CeTi₂₁O₃₈-PbTiO₃陶瓷材料电阻率的降低, 测试结果还首次给出了La₂Ti₆O₁₅-CeTi₂₁O₃₈-PbTiO₃陶瓷材料中各元素结合能位置的峰值. TG-DTA热分析表明La₂Ti₆O₁₅-CeTi₂₁O₃₈-PbTiO₃陶瓷材料具有较好的高温热稳定性.     

Bi2WO6量子点(QDs)修饰Bi2MoO6-xF2x异质结的构筑及其催化活性增强机理

采用简单沉积-沉淀法合成了Bi₂WO₆@Bi₂MoO_6-xF_2x（BWO/BMO6-xF2x）异质结,借助XRD、XPS、TEM、SEM、EDS、UV-Vis-DRS、PC和EIS等测试技术对其组成、形貌、光吸收特性和光电化学性能等进行系统表征,并以模型污染物罗丹明B（RhB）的光催化降解作为探针反应来评价Bi₂WO₆@Bi₂MoO_6-xF_2x异质结的光催化活性增强机制。形貌分析表明,所得Bi₂MoO₆微球由大量厚度为20~50 nm的纳米片组成;FE-SEM和HR-TEM分析表明,尺寸约为10 nm的Bi₂WO₆量子点均匀沉积在Bi₂MoO_6-xF_2x微球表面,形成新颖的Bi₂WO₆@Bi₂MoO_6-xF_2x异质结;与纯Bi₂MoO₆或者Bi₂WO₆相比,1∶1Bi₂WO₆@Bi₂MoO_6-xF_2x异质结表现出更好的光催化活性和光电流性质,其对RhB光催化降解的表观速率常数分别为纯BMO和BWO的6.4和11.6倍。PC和EIS图谱分析表明,Bi₂WO₆量子点表面沉积显著提高Bi₂MoO_6-xF_2x光生电子/空穴的分离效率和迁移速率;活性物种捕获实验证明了·O₂^-和h⁺是主要的活性物种。根据实验结果,探讨了F^-掺杂和Bi₂WO₆量子点之间的协同效应对Bi₂MoO₆的光催化活性的影响机制。     

o-ZrW1.6Mo0.4O8·H2O正交相的合成与表征

The precursor ZrW_1.6Mo_0.4O₇(OH)₂(H₂O)₂ was characterized by IR and XRD methods. δ′-ZrW_1.6Mo_0.4O₈ was prepared by careful controlling the annealing conditions from the precursor and was determined to have the formula as o-ZrW_1.6Mo_0.4O₈·H₂O by TG-DSC, IR, and XRD methods. The relation between o-ZrW_1.6Mo_0.4O₈·H₂O and o-ZrW_1.6Mo_0.4O₈ was discussed through variable temperature XRD patterns. Further more, the mechanism of the precursor dehydration was suggested.     

298.15 K Li2B4O7-MgCl2-H2O体系热力学性质的电动势法测定及离子相互作用模型的研究

测定了298.15 K下, 无液接电池Li-ISE│Li₂B₄O₇ (m_A)(aq.), MgCl₂(m_B)(aq.)│AgCl/Ag的电动势, 利用测定结果计算了Li₂B₄O₇-MgCl₂-H₂O体系离子强度在0.05～3 mol•kg^－1范围内, 不同MgCl₂离子强度分数的溶液中LiCl的平均活度系数, 并给出了其随离子强度I, B₄O₇^2－和Mg^2＋浓度的变化规律. 结合以往关于该体系和Li₂B₄O₇-LiCl-H₂O, Li₂B₄O₇-H₂O体系的等压研究结果, 用迭代和多元线性回归方法对Li^＋-Mg^2＋-Cl^－-B₄O₇^2－-H₂O体系的离子相互作用模型进行了研究. 具体方法为考虑了该体系在不同的总硼浓度范围H₃BO₃, B(OH)₄^－, B₃O₃(OH)₄^－和B₄O₅(OH)₄^2－四种含硼化合物的存在以及各硼化合物间的化学平衡, 以修正了的Pitzer渗透系数方程和活度系数方程为基础, 对该体系的等压法和电动势法研究结果进行最小二乘拟合, 拟合的标准偏差为0.0167, 用该模型计算的该体系的渗透系数、活度系数与实验值基本一致.     

由大环配体[As4W40O140]28-与NiII形成的新型超大杂多化合物

在pH = 4.0的水溶液中, NiCl₂·6H₂O, NH₄Cl与Na₂₇[NaAs₄W₄₀O₁₄₀]·60H₂O反应, 得到了新的杂多砷钨酸盐(NH₄)₂₀[Na₂(H₂O)₂Ni(H₂O)₅{Ni(H₂O)}₂As₄W₄₀O₁₄₀]·61H₂O单晶, 用X射线单晶衍射法及元素分析确定了其结构, 晶体属三斜晶系, P¹空间群; 其晶胞参数为: a = 1.33135(18), b = 1.9722(3), c = 3.6430(5) nm, α = 78.010(2)°, β = 82.145(2)°, γ = 74.385(2)°, V = 8.978(2) nm3, Z = 2, R1 = 0.0512, wR2 = 0.0684 (I > 2σ). 在聚阴离子[Na₂(H₂O)₂Ni(H₂O)₅{Ni(H₂O)}₂As₄W₄₀O₁₄₀]^20-中, 2个Ni²⁺和2个Na⁺分占大环配体[As₄W₄₀O₁₄₀]^28-内的4个S2空位, 每个S2位提供4个O_d向金属离子配位, 2个Ni²⁺的配位数为6, 两个Na⁺的配位数分别为5和6, 另一个Ni²⁺处于环外, 与[As₄W₄₀O₁₄₀]^28-的一个端基氧(O_d)桥连成键, 其配位数为6.     

Effect of fullerene coating on silicon thin film anodes for lithium rechargeable batteries

To improve the electrochemical performances of Si thin film anodes for lithium rechargeable batteries, fullerene thin films are prepared by plasma-assisted evaporation methods to be used as coating materials. Analyses via Raman and X-ray photoelectron spectroscopy indicate that amorphous polymeric films originated from fullerene are formed on the surface of the silicon thin film. The electrochemical performance of these fullerene-coated silicon thin film as an anode material for rechargeable lithium batteries has been investigated by cyclic voltammetry, charge/discharge tests, and electrochemical impedance spectroscopy. The fullerene-coated Si thin films demonstrated a high specific capacity of above 3,000 mAh g⁻¹ as well as good capacity retention for 40 cycles. In comparison with bare silicon anodes, the fullerene-coated silicon thin film showed superior and stable cycle performance which can be attributed to the fullerene coating layer which enhances the Li-ion kinetic property at the electrode/electrolyte interface.     

全氟烷基膦酸锂电解液的制备与性能研究

选取氯代二异丙基膦(C6H14PCl)为原料, 利用电化学氟化方法, 得到全氟烷基膦酸[(C3F7)2PF3], (C3F7)2PF3与氟化锂(LiF)反应得到全氟烷基膦酸锂(Li[(C3F7)2PF4]), 将其溶于碳酸乙烯酯(EC)和碳酸二甲酯(DMC)质量比为1∶1的混合溶剂中得到电解液, 考察电解液的电导率、抗水性及氧化分解电位. 以LiCoO2为正极, 锂片为负极组装两电极模拟电池体系, 测试得到电池的放电平台为3.7 V; 电池的首次放电比容量为107 mA•h•g－1; 当循环放电40次后, 容量衰减较快, 电池循环50周后, 效率仍保持102%. 交流阻抗图谱表明电解液放电时的阻抗约为140 Ω. 研究结果表明, 全氟烷基膦酸锂有望成为新型锂离子二次电池的电解质盐.     

多酚类化合物—丹宁酸用作锂金属负极电解液成膜添加剂

As the application of lithium-ion batteries in advanced consumer electronics, energy storage systems, plug-in hybrid electric vehicles, and electric vehicles increases, there has emerged an urgent need for increasing the energy density of such batteries. Lithium metal anode is considered as the "Holy Grail" for high-energy-density electrochemical energy storage systems because of its low reduction potential (-3.04 V vs standard hydrogen electrode) and high theoretical specific capacity (3860 mAh·g^-1). However, the practical application of lithium metal anode in rechargeable batteries is severely limited by irregular lithium dendrite growth and high reactivity with the electrolytes, leading to poor safety performance and low coulombic efficiency. Recent research progress has been well documented to suppress dendrite growth for achieving long-term stability of lithium anode, such as building artificial protection layers, developing novel electrolyte additives, constructing solid electrolytes, using functional separator, designing composite electrode or three-dimensional lithium-hosted material. Among them, the use of electrolyte additives is regarded as one of the most effective and economical methods to improve the performance of lithium-ion batteries. As a natural polyphenol compound, tannic acid (TA) is significantly cheaper and more abundant compared with dopamine, which is widely used for the material preparation and modification in the field of lithium-ion batteries. Herein, TA is first reported as an efficient electrolyte film-forming additive for lithium metal anode. By adding 0.15% (mass fraction, wt.) TA into the base electrolyte of 1 mol·L^-1 LiPF₆-EC/DMC/EMC (1 : 1 : 1, by wt.), the symmetric Li|Li cell exhibited a more stable cyclability of 270 h than that of only 170 h observed for the Li|Li cell without TA under the same current density of 1 mA·cm^-2 and capacity of 1 mAh·cm^-2 (with a cutoff voltage of 0.1 V). Electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy, cyclic voltammetry (CV), and energy-dispersive X-ray spectroscopy (EDS) analyses demonstrated that TA participated in the formation of a dense solid electrolyte interface (SEI) layer on the surface of the lithium metal. A possible reaction mechanism is proposed here, wherein the small amount of added polyphenol compound could have facilitated the formation of LiF through the hydrolysis of LiPF₆, following which the resulting phenoxide could react with dimethyl carbonate (DMC) through transesterification to form a cross-linked polymer, thereby forming a unique organic/inorganic composite SEI film that significantly improved the electrochemical performance of the lithium metal anode. These results demonstrate that TA can be used as a promising film-forming additive for the lithium metal anode.     

脉冲激光沉积法制备SnSe薄膜电极及其电化学性质

采用脉冲激光溅射Sn和Se粉末的混合靶制备SnSe薄膜, XRD结果显示室温下得到的是Sn和Se的混合薄膜, 当基片温度为200 ℃时, 薄膜主要由晶态的SnSe组成. 该薄膜的首次放电容量为498 mAh•g-1, 30次循环之后的放电容量为260 mAh•g-1. 充放电测试、循环伏安曲线和ex-situ XRD结果显示, SnSe能够和Li发生可逆的电化学反应, 充电过程中能够重新生成SnSe, 表现出不同于其它氧族元素锡化物的电化学性质.     

Electrolyte Regulation towards Stable Lithium-Metal Anodes in Lithium–Sulfur Batteries with Sulfurized Polyacrylonitrile Cathodes

Lithium–sulfur (Li–S) batteries are highly regarded as the next-generation energy-storage devices because of their ultrahigh theoretical energy density of 2600 Wh kg⁻¹. Sulfurized polyacrylonitrile (SPAN) is considered a promising sulfur cathode to substitute carbon/sulfur (C/S) composites to afford higher Coulombic efficiency, improved cycling stability, and potential high-energy-density Li–SPAN batteries. However, the instability of the Li-metal anode threatens the performances of Li–SPAN batteries bringing limited lifespan and safety hazards. Li-metal can react with most kinds of electrolyte to generate a protective solid electrolyte interphase (SEI), electrolyte regulation is a widely accepted strategy to protect Li-metal anodes in rechargeable batteries. Herein, the basic principles and current challenges of Li–SPAN batteries are addressed. Recent advances on electrolyte regulation towards stable Li-metal anodes in Li–SPAN batteries are summarized to suggest design strategies of solvents, lithium salts, additives, and gel electrolyte. Finally, prospects for future electrolyte design and Li anode protection in Li–SPAN batteries are discussed.     

Electrolyte Regulation towards Stable Lithium‐Metal Anodes in Lithium–Sulfur Batteries with Sulfurized Polyacrylonitrile Cathodes

Lithium–sulfur (Li–S) batteries are highly regarded as the next‐generation energy‐storage devices because of their ultrahigh theoretical energy density of 2600 Wh kg^?1. Sulfurized polyacrylonitrile (SPAN) is considered a promising sulfur cathode to substitute carbon/sulfur (C/S) composites to afford higher Coulombic efficiency, improved cycling stability, and potential high‐energy‐density Li–SPAN batteries. However, the instability of the Li‐metal anode threatens the performances of Li–SPAN batteries bringing limited lifespan and safety hazards. Li‐metal can react with most kinds of electrolyte to generate a protective solid electrolyte interphase (SEI), electrolyte regulation is a widely accepted strategy to protect Li‐metal anodes in rechargeable batteries. Herein, the basic principles and current challenges of Li–SPAN batteries are addressed. Recent advances on electrolyte regulation towards stable Li‐metal anodes in Li–SPAN batteries are summarized to suggest design strategies of solvents, lithium salts, additives, and gel electrolyte. Finally, prospects for future electrolyte design and Li anode protection in Li–SPAN batteries are discussed.     

Effects of current densities on the formation of LiCoO<Subscript>2</Subscript>/graphite lithium ion battery

The activation characteristics and the effects of current densities on the formation of a separate LiCoO₂ and graphite electrode were investigated and the behavior also was compared with that of the full LiCoO₂/graphite batteries using various electrochemical techniques. The results showed that the formation current densities obviously influenced the electrochemical impedance spectrum of Li/graphite, LiCoO₂/Li, and LiCoO₂/graphite cells. The electrolyte was reduced on the surface of graphite anode between 2.5 and 3.6 V to form a preliminary solid electrolyte interphase (SEI) film of anode during the formation of the LiCoO₂/graphite batteries. The electrolyte was oxidized from 3.95 V vs Li⁺/Li on the surface of LiCoO₂ to form a SEI film of cathode. A highly conducting SEI film could be formed gradually on the surface of graphite anode, whereas the SEI film of LiCoO₂ cathode had high resistance. The LiCoO₂ cathode could be activated completely at the first cycle, while the activation of the graphite anode needed several cycles. The columbic efficiency of the first cycle increased, but that of the second decreased with the increase in the formation current of LiCoO₂/graphite batteries. The formation current influenced the cycling performance of batteries, especially the high-temperature cycling performance. Therefore, the batteries should be activated with proper current densities to ensure an excellent formation of SEI film on the anode surface.     

Lithium Azide as an Electrolyte Additive for All‐Solid‐State Lithium–Sulfur Batteries

Of the various beyond‐lithium‐ion battery technologies, lithium–sulfur (Li–S) batteries have an appealing theoretical energy density and are being intensely investigated as next‐generation rechargeable lithium‐metal batteries. However, the stability of the lithium‐metal (Li°) anode is among the most urgent challenges that need to be addressed to ensure the long‐term stability of Li–S batteries. Herein, we report lithium azide (LiN₃) as a novel electrolyte additive for all‐solid‐state Li–S batteries (ASSLSBs). It results in the formation of a thin, compact and highly conductive passivation layer on the Li° anode, thereby avoiding dendrite formation, and polysulfide shuttling. It greatly enhances the cycling performance, Coulombic and energy efficiencies of ASSLSBs, outperforming the state‐of‐the‐art additive lithium nitrate (LiNO₃).     

聚1,5-二氨基蒽醌二次锂电池正极材料研究

采用化学氧化方法合成了聚1,5-二氨基蒽醌(PDAAQ)并用于二次锂电池.借助红外光谱确定其分子结构,实验测得材料的平均粒径为7.9μm,比表面积为8.9 m2.g-1,具有0.8 S.cm-1的电导率,符合作为电极材料使用的基本要求;电化学测试表明,作为二次锂电池正极材料使用时,聚合物重复单元中除了醌基团与Li+所发生的电化学氧化还原反应外,聚苯胺导电骨架也对PDAAQ的能量密度和循环性产生贡献.充放电曲线则进一步确定了聚苯胺骨架与醌基团协同作用的存在,实验表明,在Li(CF3SO2)2N/PC+DGDM电解液中,基于活性材料PDAAQ的首次放电容量达到221 mAh.g-1,经过40次充放电循环,容量保持率为80%,因此聚1,5-二氨基蒽醌具有较大应用潜力.     

金属锂负极失效机制及其先进表征技术

尽管传统的石墨负极在商业化锂离子电池中取得了成功,但其理论容量低(372 mAh·g^?1)、本身不含锂的先天缺陷限制了其在下一代高比能量锂电池体系中的应用,特别是在需要锂源的锂-硫和锂-空气电池体系中。金属锂因其极高的理论比容量(3860 mAh·g^?1)和低氧化还原电势(相对于标准氢电极为?3.040 V),被认为是下一代锂电池负极材料的最佳选择之一。但是,金属锂负极存在库伦效率低、循环性能差、安全性差等一系列瓶颈问题亟待解决,而循环过程中锂枝晶的生长、巨大的体积变化、以及电极界面不稳定等是导致这些问题的关键因素。本文综述了近年来关于金属锂负极瓶颈问题及其机理,包括金属锂电极表面固态电解质界面膜的形成,锂枝晶的生长行为,以及惰性死锂的形成。同时,本文还介绍了目前用于研究金属锂负极的先进表征技术,这些技术为研究人员深入认识金属锂负极的失效机制提供了重要信息。